1. Field of the Invention
The present invention relates to a receiver apparatus and a receiver system for receiving a radio-frequency signal such as a digital television signal.
2. Description of Related Art
FIG. 3 is a block diagram showing an outline of the configuration of a conventional receiver system. The receiver system 900 shown in FIG. 3 is composed of: an antenna 901 for receiving a radio-frequency signal; a receiver apparatus 902 for performing predetermined processing on the signal received by the antenna 901 to acquire a desired signal; and a video display apparatus 903 for performing predetermined processing on the signal acquired by the receiver apparatus 902 to extract video and audio signals.
The receiver apparatus 902 is provided with: a tuner circuit portion 911 that converts the radio-frequency signal received by the antenna 901 into an intermediate-frequency signal; a digital demodulating portion 912 that converts the intermediate-frequency signal outputted from the tuner circuit portion 911 into a compressed digital signal; and a power supply portion 913 that feeds the tuner circuit portion 911 and the digital demodulating portion 912 with electric power from which they operate. The digital demodulating portion 912 is provided with a digital demodulating IC 914, which is a processing IC for converting the intermediate-frequency signal into a digital signal.
The video display apparatus 903 is provided with: a digital circuit portion 921 that converts the compressed digital signal fed from the receiver apparatus 902 into digital video and audio signals; a video/audio output circuit 922 that converts the digital video and audio signals outputted from the digital circuit portion 921 into analog video and audio signals; a display processing portion 923 that performs processing for displaying video based on the analog video signal outputted from the video/audio output circuit 922; an audio processing portion 924 that performs processing for outputting audio based on the analog audio signal outputted from the video/audio output circuit 922; and a power supply portion 925 that feeds the digital circuit portion 921, the video/audio output circuit 922, the display processing portion 923, and the audio processing portion 924 with electric power from which they operate. The digital circuit portion 921 is provided with: a video/audio processing IC 928 for extracting video and audio signals from the compressed digital signal; a video/audio processing memory 926 for temporarily storing data being processed during video/audio processing; and a program memory 927 for storing control codes for controlling the receiver apparatus.
In this conventional receiver system 900 configured as described above, the receiver apparatus 902 is electromagnetically shielded by being covered with a shield. On the other hand, the video display apparatus 903 has many functional blocks mounted on the circuit board thereof, namely the video/audio processing IC 928, the video/audio processing memory 926, the program memory 927, the video/audio output circuit 922, the display processing portion 923, and the audio processing portion 924. This requires an accordingly large number of components and conductors to be mounted and laid on the circuit board of the video display apparatus 903, which thus necessitates the use of a multiple-layer circuit board.
Moreover, the above-mentioned functional blocks mounted on the circuit board of the video display apparatus 903, namely the video/audio processing IC 928, the video/audio processing memory 926, the program memory 927, the video/audio output circuit 922, the display processing portion 923, and the audio processing portion 924, generate unnecessary electromagnetic emission and noise, against which measures need to be taken on the video display apparatus 903 as by providing it with an additional shield.
Furthermore, the above-mentioned functional blocks mounted on the circuit board of the video display apparatus 903, namely the video/audio processing IC 928, the video/audio processing memory 926, the program memory 927, the video/audio output circuit 922, the display processing portion 923, and the audio processing portion 924, also generate heat, against which measures need to be taken as by increasing the area of the circuit board or providing it with an additional heat-dissipating plate.